Pros
I worked with great people who taught me a lot not only about my job and new things I wanted to learn, but also about life and how to be a better person.
Cons
I worked at Mapbox for four years. It started out fantastic but after the first year things started to deteriorate. A new "CEO-in-waiting" (so the founder could chillax more) joined the company and brought Amazon-style treatment of employees. Everything became about metrics and constantly having to defend yourself and your team in front of the entire engineering org in big meetings. My team, IT, was left out in the cold for six months when our manager left to manage a different team. Then, when they finally decided to hire us a manager, we had no voice in the process and the CEO-in-waiting hand-picked someone they had worked with at a prior company. All three of us with the most at stake had voted to not hire this person, but we were overruled. At Mapbox, don't bother to speak up about things that should change or stand up for your or other employees who are being mistreated. It will be met with platitudes and swept under the rug. Mid-level managers are not empowered to do anything that might contradict upper management's goals.